Act 1-Like toader said good act plus duels, also you get to go to tristram which is totally awesome.
Act 4-Short, kind of creepy, and just plain fun.
Act 5-Love the caves and Arreat Summit is just awesome, though not enough to beat out act 1 or 5, mainly because I absolutely hate arreat plateau and especially frozen tundra, I can never ever find the dang wp cuz of all the snow.
Act 3-Coolest part is Trav and the underground temples, the jungle and the new HUGE durance are big turnoffs though.
They all suck. act1 is just grass plains in a square unendlessly. Act 2 has dumb maggot lair. Act 3 is just........too much kurast boxes. Act 4 is just 4 parts and 3 of them are boxes of unendless plains. Act 5 is too easy. The only cool thin is the ancients.
ACT1: Who could resist killing slow-a** zombies in a background of nice, green grass? I know I can't. This is just about the only act I actually like to play through.
ACT4: The dark and red background is a turnoff, but it's short and the monsters are easy, except for the occasional mages casting IM on you, so that's good.
ACT2: It's a little too long, and I hate walking through the narrow maggot lair a lot, but I still don't cease to be amazed by the amazingness (lol) of the Arcane Sanctuary. The Canyon of the Magi is also cool, for racking up good exp when you're of a certain level.
ACT3: I gotta admit that the idea of a jungle is very cool, and the music is great here too, but it's just way too damn long, and unless you're playing with a party, you're gonna need some nice area damage attacks.
ACT5: Sucks. The bright, white snow in the outside areas blind me, even when my monitor's brightness is really low. There are stygian furies in some of the inside places, which cast blood mana, which really really sucks. There are lots of Black Souls and Burning Souls in there, and especially in hell mode, they can really hurt. The only good place here is Throne of Destruction for the exp and the Bloody Foothills.
Act 2=I love mummies, I love deserts, I love poison, I love skeletons and I love that Duriel sounds like the Cannibal Corpse-"singer" when he says "Looooking for Baaaal?". And of course the fact that the restless youth apartment hates it
Act 5=Ice is nice and the siege environment is really nice cause it gives you the feeling of being in battle (at least when you're not soloing).
Act 1=The best music (the acoustic guitar parts), caves that you want to live in and strange torture equipment in The jail (De Sade! De Sade! Go sadism, leather and handcuffs!).
Act 3=Jungles are cool, and I love smacking those screaming little fellows with some max fpa zeal Also, the swamp makes me wanna move into some slimy dungeon and study necromancy
Act 4=Too short, and boring enemies. No real threat, but lots and lots of life. I love that the statues on on both sides of the path to Chaos sanctuary turn their heads and gaze at you though And hell is hell, warm, red and... hellish. I have to say that I love this one too, even though it's ranked as number five.
Opinions are based in original D2expac and not the current v1.10 ...
Act1: This is the act that most resembles the original Diablo game. I like how it starts off in the wilderness and then the "evilness" of the land gradually builds up as you enter the Monastary and eventually into the Jails and Catacombs. The Blacksmith brings back memories of the Butcher. For the most part, if you played at night with the lights out, you can feel the original Diablo atmosphere.
Act4: Similar to act1 since act4 is the D2 equivelent of last D1 levels. In the D1, they were called Hell and now it looks even cooler. Again, the settings atmosphere just feels right since its the climax of the game.
Act2: This act because the atmosphere was there whenever I was in the tomb maps (Tal Rasha tombs, Halls of Dead, Viper Temple etc). The evil just seems more threatening in enclosed spaces. Also, if you listen to NPCs tell the story, the atmosphere matches the above 2 acts. The first time I played it through, I really felt uneasy about going into Tal Rasha's Tomb. If they're weren't so much open desert, this act would rank higher but I guess if you want hidden tombs in the story, you need to have far ranging deserts. The quests fit very well with that theme of this act. If only palace music didn't suck so much ...
(As a bonus, the Arcane Sanctuary is a tribute the an artist who's name escapes me - its the dude that made all those "impossible paintings" like stairs that always go up but come back the the same level)
Act5: Outstanding Worldstone Keep maps. Rest of the act didn't contain much variety unless you do Nithlaks's Temple. Shenk quest, in terms of gameplay (not the reward) is the most worthless quest, considering those catapults kept attacking even after you kill him (the catapults in frigid highlands). Basically, this act doesn't get interesting until you fight the Ancients.
Act3: Same as Act5, this act is really lame until you find the Travincal and go down the steps. Then it starts to feel like you're fighting some real evil. For some reason, the jungle and its creatures just don't have the same effects as the other settings. However it was kind of accurately done such as: you could easily get lost just like in a real jungle. Mephisto was also a wuss. I had a much harder time killing the council members. Bremn Sparkfist liked to spawn with conviction and there would usually be another boss/champion pack of Blood Lords and if you were really unlucky, dolls. They were the only real challenge in this act. Too bad.
A3 = I love the atmosphere of the jungle, especially when it is raining. Exploring the abandoned cities and temples is fun also. The Jungles of Kurast are also home to the Necromancers, my favorite class. Of course, Alkor lives here too.
A2 = I appreciate the atmosphere here as well. Tomb-raiding is fun.
A4 = Hell is a cool looking place, I should invest in some real estate here. Seriously, A4 is far too short but I like the monsters here. Great quest rewards too. Chaos Sanctuary is hella dangerous if you are melee, but it's also alot of fun.
A5 = While I can't stand the outdoor zones (I find it monotonous for some reason), I love fighting in the cave areas.
A1 = Every character starts his/her career here. For some reason I always grow bored with A1 because it never seems to end. It probably takes me longer to clear out this act than any other. On the other hand, I agree with Fearox that the jail areas have some great eye candy for those who choose to pay attention.
Moo-Moo Farm = I have never, EVER enjoyed cowing. The need for socketables is about the only reason I ever go here. Great easter egg, but as soon as it stops being funny it also stops being fun.
act1- fun, usually quick, holds a very special place in my hear. :love:
act2- meh, I don't mind playing it and it has decent music but it gets kind of boring.
act3- my second favourite after act5, I don't know why I just enjoy it.
act4- meh, quick run through and lkill everything, do quests, on to act 5.
act5- My personal favourite, most fun quests, straightforward without tons of pointless walking, decent tunes..In order of fav to least it is: 5,3,1,2,4
Strangely enough, I rank the acts in order. Lo, how far Act 5 has fallen.
Act 1! My favorite!
Pros - Tight graphics space, good mix of monsters, excellent learning curve, well designed town area. Secret cow level. Tristram in flames, and Wirt missing a few more limbs. Best quest design with no gateway quests. Corrupted rogues are tangy, rogue mercenaries are tarty. Charsi's not wearing much under that apron.
Cons - Few. Magic-finding imbalances, mostly... pit runs in spite of the many nerfed 1.10 superuniques in this act.
Act 2! I enjoy it more than most.
Pros - Desert theme. Music! Harem. Arcane Sanctuary is charity for low-end computer users like me. Lut Gholein is the most convincing interpretation of actual human civilization in the Diablo series so far. Fara's blouse says "Look..."; Fara's hammer says "... but don't touch."
Cons - Lots of flaws in act 2, mostly minor. Elemental imbalance; too much poison and fire resistance, too many undead. Good for holybolters, bad for firebolters. Worst quest design in the game-- once you kill Radament, it's all one big quest pathetically masquerading as five smaller ones. If I wanted linear I'd go play Diablo 1 again. Burning Undead swarming the final area and throwing the risk-to-reward ratio all off. Leopard women are a few purrs short of the cat's meow. Two serious flaws: TWO irritating gateway quests. Overpowered mercs.
Act 3! It's really not all that bad.
Pros - Decent quest design, almost as good as act 1's. Geographically interesting area generation. Dead giant frogs hanging in town. Hratli's sense of humor, and Asheara's thing for long slinky, slithery things.
Cons - Only one merc worth using. The decent quest design is overshadowed by the act's needless length and monotonous jungle running. 1.10 NM & Hell Durance is inexcusable. Popping dolls smell like sloppy coding. Travincal runs sure make act 3's gateway quest look like a dumb idea in hindsight.
Act 4! At least it's short.
Pros - Climactic battle. Chaos Sanctuary is a classic final battleground. A tough mix of monsters well suited for a fast, explosive finish. Best act boss in the game. Moving statues. Non shatter proof windows. Shortness is one of this act's best assets.
Cons - Anticlimactic in expansion. Venom Lords spawning in areas too low for them. Too many monsters with ranged attacks, not enough up-close enemies. Graphics bloat from River of Flame onwards. Pathetic town.
Act 5! I've run out of good things to say.
Pros - The music is nice. The town is nice. The bunnies are cute. The armorer reminds me of my state's new governor. I like snow. New expansion enemies are well designed.
Cons - Outrageous graphics bloat everywhere. Flat voice acting makes Jamella and Halbu sound like they're on uppers. 1.10 gutted the best quest in the act, converting it into another frustrating gateway quest. Throne of Destruction isn't a classic final battleground... like Baal is of Diablo, it's just a half-assed imitation borrowing every other RPG's tricks. Innovative new expansion enemies got sacked in 1.10 NM & Hell in favor of tired old ones with buggy upgrades. Sad.
1) Act 3 - Laugh away but the flayer jungle is a gold mine (in terms of items/runes) with a quick killing mf character because of the insane monster density and bugged double drops from champ/boss shamans.
2) Act 1 - This place just has a nice atmosphere to it with big open field/forest areas. It also contains the pit which is a big bonus
3) Act 4 - A short act but contains some of the toughest challenges this game can throw at you ie. oblivion knights, venom lords and burning souls.
4) Act 2 - I rate this the way that most people rate act 3. The act is just one endless boring desert with the same bland yellowish color. The monsters are extremly annoying especially the baby maggots which give no xp or items.
5) Act 5 - I rate this act in last place simply because the challenge/reward ratio is laughably enormous (huge challenge, pathetic rewards). Every monster is on steroids in terms of speed and damage and come in fat packs with multiple bosses doing 2452262626 damage. I would not have a problem with this if monsters had some decent consistency for worthwhile drops instead of fighting a death lord boss pack and being rewarded with a magical short bow, or clearing out the icy cellar in an 8 player game and not even finding worthwhile items to sell for gold.
Act 4: I was a huge Diablo 1 fan and I played it to death but the one thing that always bugged me was the highly anticlimatic battle with Diablo. He was just too easy. The first time I entered the Chaos Sanctuary in D2 it gave a major rush and a feeling of anticipation that I can still remember. When Diablo finally showed up and continued to beat the crap out of me, I was happy. Finally Diablo was a worthy opponent. That feeling can't ever be beaten, and therefore act 4 is the best. The whole act is nice and the size is just perfect, and it's the first place decent items start dropping.
Act 1: The music reminds of Diablo 1, again because of nostalgic feelings. Add to that Tristam and the demise of that little annoying bugger of a Wirt and you have a recipe for success. Besides who doesn't love the looks of Andarial. A definite place 2.
Act 2: This act, although huge, brought a whole new dimension to Diablo and I find it attractive ever seen I saw the very first screenshots, years and years ago. Besides it is the home of my beloved enemy Ancient Kaa the Soulless. The sadistic bastard that is an expert in killing characters. We have a love/hate relationship. The only reason I don't rate this act as high as the previous two is the terrible Maggot Lair. Whoever designed that must have the twisted of minds.
Act 5: I loved it the day the expansion came out but I think that was due to the fact that I uttery loved my new assassin. The graphics are good and the Ice areas are fantastic. The open areas are horrid and have only become worse in 1.10. The ancients are possible the best quest in Diablo 2 however, and the World Stone keep is good too.
Act 3: This act is just terrible until you reach Kurast but even then things don't get much better. The areas have nice artwork but are too boring to keep my attention. The council is cool, so is Mephisto's Durance. Two thumbs down for whoever though of that Khalim's Flail quest.
Although, still The Catacombs in Diablo 1 rock all acts put together